....best oils you can run are those already formulated with the right amount of zinc. . . .
A formula is just a list of additives placed into base stock after refining. There is nothing special about zinc provided by the refiner versus zinc added to the crank case.
I find the debates over at:
Bob is the Oil Guy instructive when to comes oil myths and legends.
When it comes to the need for zinc - the mid 2000s API spec simply doesn't provide enough of it. 600ppm is considered minimum for a flat tappet cam. But from what I have gleaned from research - one needs to start with 1400ppm to still have 600 parts left at the end of the oil change interval. And one needs even more zinc if the valve-spring/lifter-foot pressures are greater then stock.
One should also keep in mind why the zinc/phosphorus was 'engineered' out of the formulation in the first place - deleterious effects on catalytic converter efficiency.
Moreover, when it comes to an engine without full flow filtration - detergents are not your friend - as they are designed to suspend dirt so that it is captured by a filter. Absent a filter one needs non-detergent oil that will deposit dirt in the pan prior to it entering the sump pickup.
I will be running TSC Traveller straight 20 (mineral oil) with ZDDPplus additive. I assembled the engine using their Zpaste product on the valve train. First fire-up will take place this spring.
